\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(150:1.5){A}
    \tkzDefPoint(95:1.5){B}
    \tkzDefPoint(330:1.5){C}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawSegments[dashed](O,A  O,B  O,C)
    \tkzDrawPoint(O)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[above](B)
    \tkzLabelPoints[right](C)
    \tkzLabelPoints[below left](O)
\end{tikzpicture}

